Phase Shift Impact on the Performance of Time Modulated Antenna Arrays Driven by Radio Over Fiber

Abstract

The joint exploitation of Radio over Fiber (RoF) and Time Modulated Arrays (TMA) is proposed, showing how, particularly within In-Building scenarios, it allows to combine the pervasiveness of the first technique with the beam-steering capability of the second. A cost-effective 3-element RoF-TMA system is presented and investigated, to realize a solution for small offices / private houses (SoHo's). It is confirmed that bringing the feed to the antennas through the RoF system keeps the possibility for the TMA to radiate power at different frequencies, in each case with a steerable maximum direction. Referring to mobile signals with RF carriers of few GHz, it is shown that to guarantee, for each of the multiple beams emitted by the TMA, a maximum deviation of 5° from its ideal direction, it is sufficient that among the output branches of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1:3{\boldsymbol{\ }}$</tex-math></inline-formula> optical splitter utilized the length difference is maintained in the range of a few millimeters.